If the pane of a glass door is broken, as by a burglar, or by the wind, or by a grocery cart, or by a delivery man, in a store such as in a supermarket grocery store, the store manager must telephone for a glass emergency service and ask for a service man to come and temporarily board up his door with plywood so as to protect the store against any illegal entry and theft. Also, in the daytime when the store is open, the broken door must be boarded up in order to protect the occupants of the store against the cold in cold weather, and against the heat in hot weather if the store is air conditioned. The door is boarded up until a glass pane installer can arrive and measure the size of the door pane area, procure a replacement glass panel, and install it.
There may be a wait of several hours after the glass door pane has been broken before an emergency service man can arrive at the scene and board up the door. In the meantime, for example, if someone has pushed a grocery cart through the front door of a supermarket in cold weather, the checkout clerks are freezing, the customers are cold, and everyone is unhappy.
The problem has become worse since the passage by most states of laws requiring that the panels of doors be made of tempered glass instead of plain sheet glass. This is a safety measure designed to protect the public against injuries caused by the breaking of plain glass which breaks up into large sheets that can cut and seriously injure people. Panes made of tempered glass shatter into small pieces that do not cut.
However, this safety measure poses a serious problem for the emergency glass replacement installer. With glass panes, the installer could carry a number of sheets of plain sheet glass and then cut them down to size to fit the door panel area. However, tempered glass door panels cannot be cut to size by the installer in the field. Instead, the installer must measure the pane area of the door, board it up, and then go back to the shop to select a tempered glass sheet of the correct size for installation in the pane area of the door.